Diffusion-weighted MR Imaging Of Kidney: Preliminary Study On Influence Factors Of Apparent Diffusion Coefficient Values In Healthy Volunteers

Purpose: To discuss the impact of age and gender on apparent diffusion coefficientvalues (ADCs) of healthy volunteers kidneys in3.0T MR. Material and Method:100healthy volunteers(50males and50females; mean age,44years old; age range,19-70years old) with normal renal function and without nephropathy and hypertensionwere divided into5groups (18-29years,30-39years,40-49years,50-59years,60-70years),each group has twenty volunteers. All subjects underwent conventional MRI andRT-MRI scan with b value of0,800sec/mm2. The ADCs of each group were tested byOne-way ANOVA. The difference of ADCs between male and female were analyzed byt test. Results: The ADC values of five groups were (2.066±0.099)×10-3mm2/s,(2.059±0.124)×10-3mm2/s,(2.034±0.103)×10-3mm2/s,(1.985±0.172)×10-3mm2/s,(1.943±0.125)×10-3mm2/s, which showed statistically significant difference (F=3.375，P<0.05). The renal ADCs of males in five groups were (2.087±0.094)×10-3mm2/s,(2.086±0.146)×10-3mm2/s,(2.042±0.117)×10-3mm2/s,(2.041±0.205)×10-3mm2/s,(1.979±0.122)×10-3mm2/s; The renal ADCs of females in five groups were(2.060±0.126)×10-3mm2/s,(2.031±0.097)×10-3mm2/s,(2.026±0.092)×10-3mm2/s,(1.929±0.115)×10-3mm2/s,(1.907±0.124)×10-3mm2/s. For different gender, although therenal ADCs of males were higher than those of females in five groups, there was nosignificant differences between males and females of kidney(P>0.05). Conclusion: TheADCs of renal parenchyma may be influenced by age and sex: with the increasing ofage, ADCs of normal kidney presented tenuous decreasing tendency, there was nosignificant differences between males and females of kidney. So the age and genderfactor should be considered in clinical application. Purpose: The aim of this study was to compare Diffusion-weighted imaging (DWI) at1.5T and3.0T on kidney by evaluating the apparent diffusion coefficient values(ADCs) and the image quality. Material and Methods: One hundred and fiftyhealthy volunteers (75males and75females; mean age,38years old; age range,18-73years old) with normal renal function and without nephropathy and hypertension weredivided into5groups (18-29years,30-39years,40-49years,50-59years,60-70years),each group has thirty volunteers. All subjects underwent FB-DWI and RT-DWIof the kidney with the b values of0，800sec/mm2both at1.5T and3.0T MR system.Imaging quality analysis was performed by measuring the signal-to-noise ratios (SNRs)and analysised by the paired-samples t test. ADC values of different parts of the kidneyswere tested by One-way ANOVA and the paired-samples t test. The agreement of ADCsof the two magnetic field strengths in different group were analysised by Pearson’scoefficient. P<0.05was considered as significant. Results: The mean SNRs ofFB-DWI in3.0T and1.5T were (66.500±14.776),(51.570±8.578), which hadstatistically difference(P<0.05); the mean SNRs of RT-DWI in3.0T and1.5T were(66.611±20.748),(44.989±11.461), which had statistically difference (P<0.05). TheADCs in the upper, the central and lower portion of kidney in1.5T MR were (1.998±0.102)×10-3mm2/s,(2.157±0.166)×10-3mm2/s,(2.050±0.183)×10-3mm2/s; which in3.0T were (2.042±0.094)×10-3mm2/s,(2.073±0.147)×10-3mm2/s,(1.947±0.086)×10-3mm2/s. Three parts of kidney in the same field strengths had not statisticalmeanings(1.5T：F=2.485，P>0.05；3.0T：F=3.107，P>0.05), and the same part of thekidneys in two field strengths had not statistical meanings (P>0.05). The ADCs of fivegroups in1.5T MR were (2.165±0.162)×10-3mm2/s,(2.145±0.157)×10-3mm2/s,(2.142±0.150)×10-3mm2/s,(2.127±0.183)×10-3mm2/s,(2.079±0.119)×10-3mm2/s; theADCs of five groups in3.0T were (2.075±0.123)×10-3mm2/s,(2.066±0.117)×10-3mm2/s, (2.033±0.108)×10-3mm2/s,(1.971±0.127)×10-3mm2/s,(1.942±0.099)×10-3mm2/s. ThePearson’s correlate coefficient of two field strength were0.796. Conclusion: TheADCs of different parts of the kidneys and five groups had no statistical meanings withthe b values of0，800s/mm2. With the increasing of age, ADCs of normal kidneypresented tenuous decreasing tendency and lower in3.0T. Furthermore, it showed goodagreement between two magnetic field strengths in the kidney and SNR at3.0T MR issuperior to1.5T.